中文摘要：

采用从头计算二阶一自旋轨道多组态准筒并微扰理论计算了碘代乙烷C2H5I分子与基态I＊（2P3/2）原子和激发态I＊（2P1/2）原子解离限相关联的势能曲线．C2H。1分子的势能曲线表明除了4Qb＋（3^43A″）态外几个低激发态都为排斥态，3Q0＋电子态在Rc—I=0．346nm处有337cm-1的一个浅势阱．3Q0＋（33AH）和1Q1（21A′，1A″）电子态的垂直激发能计算表明C2H5I分子的A带吸收谱的波长区间为33478cm-1～44150cm-1（226nm~299nm），这与实验给出的（243nm～285nm）波长区间吻合较好．

英文摘要：

The potential energy curves of C2 H5 I correlated to the dissociation limits of I（zP3/2） and I＊ （2P1/2） atom are calculated using the second-order spin-orbit multiconfiguration quasidegenerate pertur- bation theory （SO-MCQDPT）. The potential energy curves of C2H5I indicate that all the low-excited states are repulsive states except for the aQ0＋ （33A＂） state,which has a shallow minimum of 337 cm-1 at Rc-I= 0. 346 nm. The calculated vertical excitation energies of aQ0＋ （33A＂） and 1Q1 （21A＇, 11A＂） for C2 H5I indicate that the wavelength range of the A-band absorption spectrum mainly lies between 33478 cm-1 and 44150 cm-1 , i. e. , between 226nm and 299nm. This result is in good agreement with experi- mental measurement （243 nm~285 nm）.